Manganese-based advanced nanoparticles for biomedical applications: future opportunity and challenges

Manganese-derived biomaterials for tumor diagnosis and therapy

Manganese (Mn) is widely recognized owing to its low cost, non-toxic nature, and versatile oxidation states, leading to the emergence of various Mn-based nanomaterials with applications across diverse fields, particularly in tumor diagnosis and therapy. Systematic reviews specifically addressing the tumor diagnosis and therapy aspects of Mn-derived biomaterials are lacking. This review comprehensively explores the physicochemical characteristics and synthesis methods of Mn-derived biomaterials, emphasizing their role in tumor diagnostics, including magnetic resonance imaging, photoacoustic and photothermal imaging, ultrasound imaging, multimodal imaging, and biodetection. Moreover, the advantages of Mn-based materials in tumor treatment applications are discussed, including drug delivery, tumor microenvironment regulation, synergistic photothermal, photodynamic, and chemodynamic therapies, tumor immunotherapy, and imaging-guided therapy. The review concludes by providing insights into the current landscape and future directions for Mn-driven advancements in the field, serving as a comprehensive resource for researchers and clinicians.

A dual-signal optical sensing platform of CDs-MnO2 NS composites for facile detection of ascorbic acid based on a combination of Tyndall effect scattering and fluorescence

A dual-signal optical sensing platform was successfully developed for the determination of ascorbic acid (AA) based on blue fluorescent carbon dots (CDs) and manganese dioxide nanosheets (MnO2 NSs) with strong Tyndall effect (TE) scattering and fluorescence quenching capabilities. In this nanosystem, CDs-MnO2 NS composites were employed as probes to evaluate the AA concentration. Owing to the strong reduction, the presence of the target AA could reduce the MnO2 NSs to Mn2+ and induce the degradation of the MnO2 NSs, resulting in a significant decrease in the TE scattering intensity of the MnO2 NSs and the fluorescence recovery of the CDs. Therefore, a novel optical sensor based on TE scattering and fluorescence dual detectors was developed for the sensitive determination of AA. Under optimized conditions, the limits of detection (LODs) of the two modes were 113 and 3 nM, respectively. Furthermore, the dual-signal optical sensing platform was successfully applied for the detection of AA in human serum.

Chitosan-modified manganese oxide-conjugated methotrexate nanoparticles delivering 5-aminolevulinic acid as a dual-modal T1-T2* MRI contrast agent in U87MG cell detection

OBJECTIVE

Glioblastoma multiforme is a highly aggressive form of brain cancer, and early diagnosis plays a pivotal role in improving patient survival rates. In this regard, molecular magnetic resonance imaging has emerged as a promising imaging modality due to its exceptional sensitivity to minute tissue changes and the ability to penetrate deep into the brain. This study aimed to assess the efficacy of a novel contrast agent in detecting gliomas during MRI scans.

MATERIALS AND METHODS

The contrast agent utilized modified chitosan coating on manganese oxide nanoparticles. The modification included adding methotrexate and 5-aminolevulinic acid (MnO2/CS@5-ALA-MTX) to target cells with overexpressed folate receptors and breaking down excess hydrogen peroxide in tumor tissue, resulting in enhanced signal intensity in T1-weighted MR images but diminished signal intensity in T2*-weighted MR images.

RESULTS

The nanosystem was characterized and evaluated in MR imaging, safety, and ability to target cells both in vivo and in vitro. MTX-free nanoparticles (MnO2/CS@5-ALA NPs) had no obvious cytotoxicity on cell lines U87MG and NIH3T3 after 24/48 h at a concentration of up to 160 µgr/mL (cell viability more than 80%). In this system, methotrexate enables tumor targeting and the MnO2/5-ALA improves T1-T2*-weighted MRI. In addition, MRI scans of mice with M109 carcinoma indicated significant tumor uptake and NP capacity to improve the positive contrast effect.

CONCLUSION

This developed MnO2/CS@5-ALA-MTX nanoparticle system may exhibit great potential in the accurate diagnosis of folate receptor over-expressing cancers such as glioblastoma.

Synthesis, Characterization, and Catalytic Application of Colloidal and Supported Manganese Nanoparticles

Colloidal and supported manganese nanoparticles were synthesized following an organometallic approach and applied in the catalytic transfer hydrogenation (CTH) of aldehydes and ketones. Reaction parameters for the preparation of colloidal nanoparticles (NPs) were optimized to yield small (2-2.5 nm) and well-dispersed NPs. Manganese NPs were further immobilized on an imidazolium-based supported ionic phase (SILP) and characterized to evaluate NP size, metal loading, and oxidation states. Oxidation of the Mn NPs by the support was observed resulting in an average formal oxidation state of +2.5. The MnOx@SILP material showed promising performance in the CTH of aldehydes and ketones using 2-propanol as a hydrogen donor, outperforming previously reported Mn NPs-based CTH catalysts in terms of metal loading-normalized turnover numbers. Interestingly, MnOx@SILP were found to lose activity upon air exposure, which correlates with an additional increase in the average oxidation state of Mn as revealed by X-ray absorption spectroscopic studies.

Manganese Nanoparticles: Synthesis, Mechanisms of Influence on Plant Resistance to Stress, and Prospects for Application in Agricultural Chemistry

Manganese (Mn) is an important microelement for the mineral nutrition of plants, but it is not effectively absorbed from the soil and mineral salts added thereto and can also be toxic in high concentrations. Mn nanoparticles (NPs) are less toxic, more effective, and economical than Mn salts due to their nanosize. This article critically reviews the current publications on Mn NPs, focusing on their effects on plant health, growth, and stress tolerance, and explaining possible mechanisms of their effects. This review also provides basic information and examples of chemical, physical, and ecological ("green") methods for the synthesis of Mn NPs. It has been shown that the protective effect of Mn NPs is associated with their antioxidant activity, activation of systemic acquired resistance (SAR), and pronounced antimicrobial activity against phytopathogens. In conclusion, Mn NPs are promising agents for agriculture, but their effects on gene expression and plant microbiome require further research.

Nitroprusside and metal nitroprusside nano analogues for cancer therapy

Sodium nitroprusside (SNP), U.S approved drug has been used in clinical emergency as a hypertensive drug for more than a decade. It is well established for its various biomedical applications such as angiogenesis, wound healing, neurological disorders including anti-microbial applications etc. Apart from that, SNP have been considered as excellent biomedical materials for its use as anti-cancer agent because of its behavior as NO-donor. Recent reports suggest that incorporation of metals in SNP/encapsulation of SNP in metal nanoparticles (metal nitroprusside analogues) shows better therapeutic anti-cancer activity. Although there are numerous reports available regarding the biological applications of SNP and metal-based SNP analogue nanoparticles, unfortunately there is not a single comprehensive review which highlights the anti-cancer activity of SNP and its derivative metal analogues in detail along with the future perspective. To this end, the present review article focuses the recent development of anti-cancer activity of SNP and metal-based SNP analogues, their plausible mechanism of action, current status. Furthermore, the future perspectives and challenges of these biomedical materials are also discussed. Overall, this review article represents a new perspective in the area of cancer nanomedicine that will attract a wider spectrum of scientific community.

Mechanism by which HDAC3 regulates manganese induced H3K27ac in SH-SY5Y cells and intervention by curcumin

Long-term excessive exposure to manganese can impair neuronal function in the brain, but the underlying pathological mechanism remains unclear. Oxidative stress plays a central role in manganese-induced neurotoxicity. Numerous studies have established a strong link between abnormal histone acetylation levels and the onset of various diseases. Histone deacetylase inhibitors and activators, such as TSA and ITSA-1, are often used to investigate the intricate mechanisms of histone acetylation in disease. In addition, recent experiments have provided substantial evidence demonstrating that curcumin (Cur) can act as an epigenetic regulator. Given these findings, this study aims to investigate the mechanisms underlying oxidative damage in SH-SY5Y cells exposed to MnCl2·4H2O, with a particular focus on histone acetylation, and to assess the potential therapeutic efficacy of Cur. In this study, SH-SY5Y cells were exposed to manganese for 24 h, were treated with TSA or ITSA-1, and were treated with or without Cur. The results suggested that manganese exposure, which leads to increased expression of HDAC3, induced H3K27 hypoacetylation, inhibited the transcription of antioxidant genes, decreased antioxidant enzyme activities, and induced oxidative damage in cells. Pretreatment with an HDAC3 inhibitor (TSA) increased the acetylation of H3K27 and the transcription of antioxidant genes and thus slowed manganese exposure-induced cellular oxidative damage. In contrast, an HDAC3 activator (ITSA-1) partially increased manganese-induced cellular oxidative damage, while Cur prevented manganese-induced oxidative damage. In summary, these findings suggest that inhibiting H3K27ac is a possible mechanism for ameliorating manganese-induced damage to dopaminergic neurons and that Cur exerts a certain protective effect against manganese-induced damage to dopaminergic neurons.

In-vitro and in-vivo evaluation for the bio-natural Alginate/nano-Hydroxyapatite (Alg/n-HA) injectable hydrogel for critical size bone substitution

Currently, bio-natural injectable hydrogels are receiving a lot of attention due to their ability to control, adjust, and adapt to random bone defects, in addition, to their ability to mimic the composition of natural bones. From such a viewpoint, this study goal is to prepare and characterize the injectable hydrogels paste based on the natural alginate (Alg) derived from brown sea algae as a polysaccharide polymer, which coupled with nano biogenic-hydroxyapatite (n-HA) prepared from eggshells and enriched with valuable trace elements. The viscosity and mechanical properties of the paste were investigated. As well as the in-vitro study in terms of water absorption and biodegradability in the PBS, biocompatibility and the capability of the injectable Alginate/n-Hydroxyapatite (Alg/n-HA) to regenerate bone for the most suitable injectable form. The injectable hydrogel (BP -B sample) was chosen for the study as it had an appropriate setting time for injecting (13 mins), and suitable compressive strength reached 6.3 MPa. The in vivo study was also carried out including a post-surgery follow-up test of the newly formed bone (NB) in the defect area after 10 and 20 weeks using different techniques such as (SEM/EDX) and histological analysis, the density of the newly formed bone by Dual x-ray absorptiometry (DEXA), blood biochemistry and the radiology test. The results proved that the injectable hydrogels Alginate/n-Hydroxyapatite (Alg/n-HA) had an appreciated biodegradability and bioactivity, which allow the progress of angiogenesis, endochondral ossification, and osteogenesis throughout the defect area, which positively impacts the healing time and ensures the full restoration for the well-mature bone tissue that similar to the natural bone.

Toxicity study of pro-angiogenic casein manganese oxide nanoparticles: an in vitro and in vivo approach

Recently, we have demonstrated casein manganese oxide nanoparticles (CMnNP) that exhibit pro-angiogenic property established through different in vitro and in vivo experiments. The CMnNP was explored for therapeutic angiogenesis for treatment of wounds and recovery of hindlimb ischemia in pre-clinical mouse prototypical. It is well known that to translate any therapeutic nanoparticle for future clinical applications, their biosafety evaluation in small and large animals is essential. Herein, in the current study, the biosafety and bioavailability of the CMnNP have been explored by a systematic toxicity profiling study in C57BL/6J mice model. Initially, the in vitro cytotoxic effects of CMnNP were validated in RAW 264.7 cells. Later, the CMnNP was administered intraperitoneally with different doses (50, 300, and 2000 mg/kg b.wt./day) at different time points of exposure (acute: 2 weeks, sub-chronic: 4 weeks as well as chronic exposure: 8 and 20 weeks) with reference to the maximum tolerable dose (MTD) of CMnNP as per the OECD guidelines. The blood hematological and serum biochemical parameters of CMnNP treatment groups indicate negligible changes similar to untreated group. The histopathological examination of CMnNP-treated vital organs (lung, spleen, liver, brain, kidney, and heart) illustrates no major changes even at higher doses. Further, the biodistribution and excretion study depicts normal clearance of CMnNP. Additionally, the serum cytokine levels were normal in the therapeutic dose of CMnNP. The results altogether indicate that the non-toxic nature of CMnNP makes them useful as future therapeutic angiogenic agent for the treatment of various diseases where angiogenesis plays an important role.

Exploring the effect of surfactants on the interactions of manganese dioxide nanoparticles with biomolecules

Interactions of manganese dioxide nanoparticles (MnO2 NPs) with vital biomolecules namely deoxyribonucleic acid (DNA) and serum albumin (BSA) have been studied in association with different surfactants by using fluorescence (steady state, synchronous and 3D), UV-visible, resonance light scattering (RLS), dynamic light scattering (DLS), and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The esterase activity of serum albumin was tested in associations with MnO2 NPs and surfactants. The antioxidant potential of prepared NPs was also evaluated (DPPH method). Gel electrophoresis was carried out to analyze the effect of MnO2 NPs and surfactants on DNA. Presence of CTAB, Tween 20, DTAB and Tween 80 enhanced nanoparticle-protein binding. Tween 20 based nanoparticle systems showed long-term stability and biocompatibility. The quenching of BSA fluorescence emission in presence of MnO2 NPs alone and along with Tween 20 revealed stronger association of nanoparticles with proteins. Enhancement in the esterase activity (BSA) was observed in the presence of Tween 20. Furthermore, radical scavenging activity showed highest antioxidant potential in presence of Tween 20. The enthalpy and entropy assessment for protein-NPs association showed the predominance of Vander Waals interactions and hydrogen bonding. The synchronous fluorescence analysis highlighted the involvement of tryptophan (Trp) in the MnO2 NPs-protein interactions. The study evaluates the influence of surfactant on the associations of MnO2 NPs with the essential biomolecules. The findings can be crucially utilized in designing biocompatible MnO2 formulations for long term applications.Communicated by Ramaswamy H. Sarma.

Targeting ferroptosis by poly(acrylic) acid coated Mn3O4 nanoparticles alleviates acute liver injury

Ferroptosis, a newly characterized form of regulated cell death, is induced by excessive accumulation of lipid peroxidation catalyzed by intracellular bioactive iron. Increasing evidence has suggested that ferroptosis is involved in the pathogenesis of several human diseases, including acute liver injury. Targeted inhibition of ferroptosis holds great promise for the clinical treatment of these diseases. Herein, we report a simple and one-pot synthesis of ultrasmall poly(acrylic) acid coated Mn3O4 nanoparticles (PAA@Mn3O4-NPs, PMO), which perform multiple antioxidant enzyme-mimicking activities and can scavenge broad-spectrum reactive oxygen species. PMO could potently suppress ferroptosis. Mechanistically, after being absorbed mainly through macropinocytosis, PMO are largely enriched in lysosomes, where PMO detoxify ROS, inhibit ferritinophagy-mediated iron mobilization and preserve mTOR activation, which collectively confer the prominent inhibition of ferroptosis. Additionally, PMO injection potently counteracts lipid peroxidation and alleviates acetaminophen- and ischaemia/reperfusion-induced acute liver injury in mice. Collectively, our results reveal that biocompatible PMO act as potent ferroptosis inhibitors through multifaceted mechanisms, which ensures that PMO have great translational potential for the clinical treatment of ferroptosis-related acute liver injury.

Self-template sacrifice and in situ oxidation of a constructed hollow MnO2 nanozymes for smartphone-assisted colorimetric detection of liver function biomarkers

Liver function tests play a vital role in accurately diagnosing liver diseases, monitoring treatment outcomes, and assessing liver damage severity. Here, we introduce a novel approach to develop a smartphone-assisted portable colorimetric sensor for rapid detection of three liver function biomarkers: aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP). This sensor is based on the inherent enzyme-like activities of hollow MnO2 (H-MnO2). The H-MnO2 is synthesized via a self-template sacrifice and in situ oxidation strategy, utilizing a manganese-based Prussian blue analogue (Mn-PBA) as a sacrificial template. The resulting H-MnO2 exhibits a polycrystalline structure with a large specific surface area. By encapsulating the H-MnO2 in sodium alginate, we construct a portable sensing platform facilitating specific and rapid colorimetric detection of the three liver function biomarkers with the assistance of a smartphone. The developed sensor demonstrates outstanding sensitivity and stability, achieving detection limits of 4.9 U L-1, 3.6 U L-1, and 0.99 U L-1 for AST, ALT, and ALP, respectively. Importantly, this work introduces an innovative in situ oxidation method for fabricating hollow nanozymes, offering a cost-effective and convenient assay for liver function biomarkers detection.

Elemental analysis of Fadogia ancylantha leaves used as a nutraceutical in Mashonaland West Province, Zimbabwe

In this study, the concentrations of the essential elements to the human body N, K, Mg, P, Ca, Fe, Mn, and Zn of the fermented and non-fermented Fadogia ancylantha leaf samples were analysed to assess their nutritional value in two different areas in Zimbabwe: Mhangura (Mashonaland West, Province) and Alaska (Mashonaland West Province). Atomic absorption spectroscopy and ultraviolet spectrophotometry techniques were used to measure the concentrations of the minerals. The concentrations of manganese were significantly high (p < 0.05) in non-fermented treatments, with Mhangura samples having 0.447 mg/g and Alaska samples having 0.453 mg/g. Iron was high in fermented samples with Mhangura samples having 0.245 mg/g and Alaska samples having 0.270 mg/g. The concentrations of manganese and iron in Fadogia ancylantha can be used to supplement the recommended daily doses in pregnant, menstruating, and lactating women. The study, therefore, recommends that Fadogia ancylantha be used as a nutraceutical for the supplementation of iron and manganese.

Magnetically controlled drug delivery and hyperthermia effects of core-shell Cu@Mn3O4 nanoparticles towards cancer cells in vitro

Recent increase in the integration of nanotechnology and nanosciences to the biomedical sector fetches the human wellness through the development of sustainable treatment methodologies for cancerous tumors at all stages of their initiation and progression. This involves the development of multifunctional theranostic probes that effectively support for the early cancer diagnosis, avoiding non-target cell toxicity, controlled and customized anticancer drug release etc. Therefore, to advance the field of nanotechnology-based sustainable cancer treatment, we fabricated and tested the efficacy of anticancer drug-loaded magnetic hybrid nanoparticles (NPs) towards in vitro cell culture systems. The developed conjugate of NPs was incorporated with the functions of both controlled drug delivery and heat-releasing ability using Mn3O4 (manganese oxide) magnetic core with Cu shell encapsulated within trimethyl chitosan (TMC) biopolymer. On characterization, the Cu@Mn3O4-TMC NPs were confirmed to have an approximate size of 130 nm with full agglomeration (as observed by the HRTEM) and crystal size of 92.95 ± 18.38 nm with tetragonal hausmannite phase for Mn3O4 spinel structure (XRD). Also, the UV-Vis and FTIR analysis provided the qualitative and quantitative effects of 5-fluororacil (5-Fu) anticancer drug loading (max 68 %) onto the Cu@Mn3O4-TMC NPs. The DLS analysis indicated for the occurrence of no significant changes to the particle size (around 100 nm) of Cu@Mn3O4-TMC due to the solution dispersion thereby confirming for the aqueous stability of developed NPs. In addition, the magnetization values of Cu@Mn3O4-TMC NPs were measured to be 34 emu/g and a blocking temperature of 42 K. Further tests of magnetic hyperthermia by the Cu@Mn3O4-TMC/5-Fu NPs provided that the heat-releasing capacity (% ΔT at 15 min) increases with that of increased frequency, i.e. 28 % (440 Hz) > 22.6 % (240 Hz) > 18 % (44 Hz), and the highest specific power loss (SPL) value observed to be 488 W/g for water. Moreover, the 5-Fu drug release studies indicate that the release is high at a pH of 5.2 and almost all the loaded drug is getting delivered under the influence of the external magnetic field (430 Hz) due to the influence of both Brownian-rotation and Néel relaxation heat-mediated mechanism. The pharmacokinetic drug release studies have suggested for the occurrence of more than one model, i.e. First-order, Higuchi (diffusion), and Korsemeyer-Peppas (non-Fickian), in addition to hyperthermia. Finally, the in vitro cell culture systems (MCF-7 cancer and MCF-10 non-cancer) helped to differentiate the physiological changes due to the effects of hyperthermia and 5-Fu drug individually and as a combination of both. The observed differences of cell viability losses among both cell types are measured and discussed with the expression of heat shock proteins (HSPs) by the MCF-10 cells as against the MCF-7 cancer cells. We believe that the results generated in this project can be helpful for the designing of new cancer therapeutic models with nominal adverse effects on healthy normal cells and thus paving a way for the treatment of cancer and other deadly diseases in a sustainable manner.

Nano-based drug delivery system for therapeutics: a comprehensive review

Nanomedicine and nano-delivery systems hold unlimited potential in the developing sciences, where nanoscale carriers are employed to efficiently deliver therapeutic drugs at specifically targeted sites in a controlled manner, imparting several advantages concerning improved efficacy and minimizing adverse drug reactions. These nano-delivery systems target-oriented delivery of drugs with precision at several site-specific, with mild toxicity, prolonged circulation time, high solubility, and long retention time in the biological system, which circumvent the problems associated with the conventional delivery approach. Recently, nanocarriers such as dendrimers, liposomes, nanotubes, and nanoparticles have been extensively investigated through structural characteristics, size manipulation, and selective diagnosis through disease imaging molecules, which are very effective and introduce a new paradigm shift in drugs. In this review, the use of nanomedicines in drug delivery has been demonstrated in treating various diseases with significant advances and applications in different fields. In addition, this review discusses the current challenges and future directions for research in these promising fields as well.

Multi-Functional Chitosan Nanovesicles Loaded with Bioactive Manganese for Potential Wound Healing Applications

Chronic skin wound is a chronic illness that possesses a risk of infection and sepsis. In particular, infections associated with antibiotic-resistant bacterial strains are challenging to treat. To combat this challenge, a suitable alternative that is complementary to antibiotics is desired for wound healing. In this work, we report multi-functional nanoscale chitosan vesicles loaded with manganese (Chi-Mn) that has potential to serve as a new tool to augment traditional antibiotic treatment for skin wound healing. Chi-Mn showed antioxidant activity increase over time as well as antimicrobial activity against E. coli and P. aeruginosa PA01. The modified motility assay that mimicked a skin wound before bacterial colonization showed inhibition of bacterial growth with Chi-Mn treatment at a low area density of 0.04 µg of Mn per cm2. Furthermore, this study demonstrated the compatibility of Chi-Mn with a commercial antibiotic showing no loss of antimicrobial potency. In vitro cytotoxicity of Chi-Mn was assessed with macrophages and dermal cell lines (J774A.1 and HDF) elucidating biocompatibility at a wide range (2 ppm-256 ppm). A scratch wound assay involving human dermal fibroblast (HDF) cells was performed to assess any negative effect of Chi-Mn on cell migration. Confocal microscopy study confirmed that Chi-Mn tested at the MIC (16 ppm Mn) has no effect on cell migration with respect to control. Overall, this study demonstrated the potential of Chi-Mn nanovesicles for wound healing applications.

Research progress in green synthesis of manganese and manganese oxide nanoparticles in biomedical and environmental applications - A review

Nanomaterials and nanotechnology have this unassailable position for environmental remediation and medicine. Currently, global environmental pollution and public health problems are increasing and need to be urgently addressed. Manganese (Mn) is one of the essential metal elements for plants and animals, it is necessary to integrate with nanotechnology. Mn and Mn oxide (MnO) nanoparticles (NPs) have applications in dye degradation, biomedicine, electrochemical sensors, plant and animal growth, and catalysis. However, the current research is limited, especially in terms of optimal synthesis of Mn and MnO NPs, separation, purification conditions, and the development of potential application areas is too basic and do not support by in-depth studies. Hence, this review comprehensively discusses the classification, green synthesis methods, and applications of Mn and MnO NPs in biomedical, environmental, and other fields and gives a perspective for the future.

Biosynthesized metal oxide nanoparticles for sustainable agriculture: next-generation nanotechnology for crop production, protection and management

The current agricultural sector is not only in its most vulnerable state but is also becoming a threat to our environment due to expanding population and growing food demands along with worsening climatic conditions. In addition, numerous agrochemicals presently being used as fertilizers and pesticides have low efficiency and high toxicity. However, the rapid growth of nanotechnology has shown great promise to tackle these issues replacing conventional agriculture industries. Since the last decade, nanomaterials especially metal oxide nanoparticles (MONPs) have been attractive for improving agricultural outcomes due to their large surface area, higher chemical/thermal stability and tunable unique physicochemical characteristics. Further, to achieve sustainability, researchers have been extensively working on ecological and cost-effective biological approaches to synthesize MONPs. Hereby, we have elaborated on recent successful biosynthesis methods using various plants/microbes. Furthermore, we have elucidated different mechanisms for the interaction of MONPs with plants, including their uptake/translocation/internalization, photosynthesis, antioxidant activity, and gene alteration, which could revolutionize crop productivity/yield through increased nutrient amount, photosynthesis rate, antioxidative enzyme level, and gene upregulations. Besides, we have briefly discussed about functionalization of MONPs and their application in agricultural-waste-management. We have further illuminated recent developments of various MONPs (Fe₂O₃/ZnO/CuO/Al₂O₃/TiO₂/MnO₂) as nanofertilizers, nanopesticides and antimicrobial agents and their implications for enhanced plant growth and pest/disease management. Moreover, the potential use of MONPs as nanobiosensors for detecting nutrients/pathogens/toxins and safeguarding plant/soil health is also illuminated. Overall, this review attempts to provide a clear insight into the latest advances in biosynthesized MONPs for sustainable crop production, protection and management and their scope in the upcoming future of eco-friendly agricultural nanotechnology.

Antimicrobial Efficacy of Green Synthesized Nanosilver with Entrapped Cinnamaldehyde against Multi-Drug-Resistant Enteroaggregative Escherichia coli in Galleria mellonella

The global emergence of antimicrobial resistance (AMR) needs no emphasis. In this study, the in vitro stability, safety, and antimicrobial efficacy of nanosilver-entrapped cinnamaldehyde (AgC) against multi-drug-resistant (MDR) strains of enteroaggregative Escherichia coli (EAEC) were investigated. Further, the in vivo antibacterial efficacy of AgC against MDR-EAEC was also assessed in Galleria mellonella larval model. In brief, UV-Vis and Fourier transform infrared (FTIR) spectroscopy confirmed effective entrapment of cinnamaldehyde with nanosilver, and the loading efficiency was estimated to be 29.50 ± 0.56%. The AgC was of crystalline form as determined by the X-ray diffractogram with a mono-dispersed spherical morphology of 9.243 ± 1.83 nm in electron microscopy. AgC exhibited a minimum inhibitory concentration (MIC) of 0.008−0.016 mg/mL and a minimum bactericidal concentration (MBC) of 0.008−0.032 mg/mL against MDR- EAEC strains. Furthermore, AgC was stable (high-end temperatures, proteases, cationic salts, pH, and host sera) and tested safe for sheep erythrocytes as well as secondary cell lines (RAW 264.7 and HEp-2) with no negative effects on the commensal gut lactobacilli. in vitro, time-kill assays revealed that MBC levels of AgC could eliminate MDR-EAEC infection in 120 min. In G. mellonella larvae, AgC (MBC values) increased survival, decreased MDR-EAEC counts (p < 0.001), had an enhanced immunomodulatory effect, and was tested safe to the host. These findings infer that entrapment enhanced the efficacy of cinnamaldehyde and AgNPs, overcoming their limitations when used individually, indicating AgC as a promising alternative antimicrobial candidate. However, further investigation in appropriate animal models is required to declare its application against MDR pathogens.

Harnessing immune response using reactive oxygen Species-Generating/Eliminating inorganic biomaterials for disease treatment

With the increasing understanding of various biological functions mediated by reactive oxygen species (ROS) in the immune system, a number of studies have been designed to develop ROS-generating/eliminating strategies to selectively modulate immunogenicity for disease treatment. These strategies potentially exploit ROS-modulating inorganic biomaterials to harness host immunity to maximize the therapeutic potency by eliciting a favorable immune response. Inorganic biomaterial-guided in vivo ROS scavenging can exhibit several effects to: i) reduce the secretion of pro-inflammatory factors, ii) induce the phenotypic transition of macrophages from inflammatory M1 to immunosuppressive M2 phase, iii) minimize the recruitment and infiltration of immune cells. and/or iv) suppress the activation of nuclear factor kappa-B (NF-κB) pathway. Inversely, ROS-generating inorganic biomaterials have been found to be capable of: i) inducing immunogenic cell death (ICD), ii) reprograming tumor-associated macrophages from M2 to M1 phenotypes, iii) activating inflammasomes to stimulate tumor immunogenicity, and/or iv) recruiting phagocytes for antimicrobial therapy. This review provides a systematic and up-to-date overview on the progress related to ROS-nanotechnology mediated immunomodulation. We highlight how the ROS-generating/eliminating inorganic biomaterials can converge with immunomodulation and ultimately elicit an effective immune response against inflammation, autoimmune diseases, and/or cancers. We expect that contents presented in this review will be beneficial for the future advancements of ROS-based nanotechnology and its potential applications in this evolving field.

Manganese-based hollow nanoplatforms for MR imaging-guided cancer therapies

Theranostic nanoplatforms integrating diagnostic and therapeutic functions have received considerable attention in the past decade. Among them, hollow manganese (Mn)-based nanoplatforms are superior since they combine the advantages of hollow structures and the intrinsic theranostic features of Mn²⁺. Specifically, the hollow cavity can encapsulate a variety of small-molecule drugs, such as chemotherapeutic agents, photosensitizers and photothermal agents, for chemotherapy, photodynamic therapy (PDT) and photothermal therapy (PTT), respectively. After degradation in the tumor microenvironment (TME), the released Mn²⁺ is able to act simultaneously as a magnetic resonance (MR) imaging contrast agent (CA) and as a Fenton-like agent for chemodynamic therapy (CDT). More importantly, synergistic treatment outcomes can be realized by reasonable and optimized design of the hollow nanosystems. This review summarizes various Mn-based hollow nanoplatforms, including hollow Mn_xO_y, hollow matrix-supported Mn_xO_y, hollow Mn-doped nanoparticles, hollow Mn complex-based nanoparticles, hollow Mn-cobalt (Co)-based nanoparticles, and hollow Mn-iron (Fe)-based nanoparticles, for MR imaging-guided cancer therapies. Finally, we discuss the potential obstacles and perspectives of these hollow Mn-based nanotheranostics for translational applications.

Manganese dioxide nanosheet-containing reactors as antioxidant support for neuroblastoma cells

Supporting mammalian cells against reactive oxygen species such as hydrogen peroxide (H₂O₂) is essential. Bottom-up synthetic biology aims to integrate designed artificial units with mammalian cells. Here, we used manganese dioxide nanosheets (MnO₂-NSs) as catalytically active entities that have superoxide dismutase-like and catalase-like activities. The integration of these MnO₂-NSs into 7 μm reactors was able to assist SH-SY5Y neuroblastoma cells when stressed with H₂O₂. Complementary, Janus-shaped 800 nm reactors with one hemisphere coated with MnO₂-NSs showed directed locomotion in cell media with top speeds up to 50 μm s^-1 when exposed to 300 mM H₂O₂ as a fuel, while reactors homogeneously coated with MnO₂-NSs were not able to outperform Brownian motion. These Janus-shaped reactors were able to remove H₂O₂ from the media, protecting cells cultured in the proximity. This effort advanced the use of bottom-up synthetic biology concepts in neuroscience.